In LTE (Long Term Evolution) and successor systems of LTE (referred to as, for example, “LTE-advanced,” “FRA (Future Radio Access),” “4G,” etc.), a radio communication system (referred to as, for example, “HetNet” (Heterogeneous Network)) to place one or more small cells (including pico cells, femto cells and so on) having a relatively small coverage of a radius of approximately several meters to several tens of meters, within a macro cell having a relatively large coverage of a radius of approximately several hundred meters to several kilometers, is under study (see, for example, non-patent literature 1).
Given this radio communication system, a scenario to use the same frequency band F1 in both the macro cell and the small cells as shown in FIG. 1A (“co-channel”), and a scenario to use mutually different frequencies F1 and F2 between the macro cell and the small cells as shown in FIG. 1B (“separated frequencies,” “non-co-channel,” etc.) are under study. Also, in the scenario illustrated in FIG. 1B, a study is also in progress to use different frequencies F2 and F3 between the small cells.